diff --git a/chrome/bridge.js b/chrome/bridge.js
index 08e8679..101c842 100644
--- a/chrome/bridge.js
+++ b/chrome/bridge.js
@@ -8,6 +8,10 @@
 
 /* global QUnit:true */
 (function (factory) {
+  if (window.self !== window.top) {
+    // Ignore iframes. https://github.com/gruntjs/grunt-contrib-qunit/issues/202
+    return;
+  }
   if (typeof define === 'function' && define.amd) {
     require(['qunit'], factory);
   } else {